Vertical shaft impact crushers (VSI-crushers) are used in many applications for crushing hard material, such as rocks, ore etc. U.S. Pat. No. 4,690,341 describes one example of a VSI-crusher. A-VSI-crusher comprises a housing and a horizontal rotor located inside the housing. Material that is to be crushed is fed into the rotor via an opening in the top thereof. With the aid of centrifugal force, the rotating rotor ejects the material against the wall of the housing. On impact with the wall of the housing, the material is crushed to a desired size. The housing wall could be provided with anvils or have a bed of retained material against which the accelerated material is crushed.
The rotor of a VSI-crusher usually has a horizontal upper disc and a horizontal lower disc. The upper and lower discs are connected with a vertical rotor wall. The upper disc has an aperture for feeding material into the rotor. The material lands on the lower disc and is then thrown out of the rotor via openings in the rotor wall. The vertical rotor wall is provided with various replaceable wear parts of a hard material, such as a hard metal or a ceramic, to protect it from wear caused by the material leaving the rotor at a high speed. The rotor of U.S. Pat. No. 4,690,341 is provided with a number of wear parts in the form of overlapping dove tailed wear castings to protect the vertical rotor wall from abrasive particles moving at high speed within the housing of the crusher. Other rotor types, such as that described in WO 2004/020100, have wear parts positioned on specific places of the vertical rotor wall.
When the wear parts protecting the vertical rotor wall have become worn out they must be replaced. Replacement of the wear parts requires the VSI-crusher to be shut down for a considerable time for maintenance.